1. Technical Field
The present invention relates to an electrophoretic display apparatus which changes a display state by changing a distribution state of charged migration particles in an electrophoresis dispersing liquid.
2. Background of the Invention
As a nonluminous display device, an electrophoretic display apparatus using an electrophoresis phenomenon is known. The electrophoresis phenomenon is a phenomenon that charged migration particles move by a coulomb force when an electric field is applied to a dispersion liquid in which the charged migration particles are dispersed in a dispersion medium. Then, the electrophoretic display apparatus performs display based on a change of the distribution state following the movement of the charged migration particles.
FIG. 14 illustrates an example of the electrophoretic display apparatus proposed in the specification of U.S. Pat. No. 6,144,361.
FIG. 14 illustrates two pixels of the electrophoretic display apparatus. A left-hand side pixel P shows a state that charged migration particles 103 disperse in the pixel P (dark state A), and a pixel P in a right-hand side in FIG. 14 illustrates a state (bright state B) that charged migration particles 103 are gathered to an electrode 101 in the periphery of the pixel. The electrode 101 which also serves as a surrounding partition, and an inside electrode 102 are arranged in each of all the pixels. A dispersion liquid 104 containing a transparent liquid and two or more charged migration particles 103 are filled in each pixel.
In the above-described electrophoretic display apparatus, when a display state is made into the bright state B, a voltage is applied between the electrode 101 and electrode 102, and an electric field which gathers the charged migration particles 103 together to the electrode 101 in the periphery of a pixel is formed. Hence, when the same display state is repeated many times, an electric field in an identical direction is applied to the dispersion liquid 104 repeatedly, and the same electric field is formed for a long time. For this reason, ions which exist in the dispersion liquid 104 are unevenly distributed, and space charge distribution is formed and is stored as a residual DC component. Consequently, there was a problem that, when displaying next, an electric field was given modulation by the residual DC component, and displacement from a desired writing level, that is, display burn-in was generated.